Hello everyone,
my first post here, just were reading here for until now.
Im a 85kg rider doing mainly dockstarts on a F-One Jam 1900 with masts from 60cm to 85cm.
Today i sent my foil to the bottom of the lake when i heard a sudden snap and instantly hit the water with board. Didnt do anything crazy, just going straight. edit: I was on the 75cm mast today
All 3 titanium screws connecting the foil to the mast foot are clean sheard off.
See pictures:
Is it possible they were a hair too long and bottoming out before fully tightening the connection?
Thatâs a common issue for the F-one mast/fuse connection.
Youâre no flyweight and that 1900 has huge leverage. Probably best to just stick with the stock F-one stainless screws in that location.
Common issue with F-one it seems.
M6 for those kinds of load and minimal foot support putting a lots of load on those.
Titanium is not necessarily stronger than steel, main advantage is corrosion (esp carbon foil, aluminum fuse) and weight (negligible for bolts).
Titanium like carbon snap without warning.
Why does F-one (and Gong) keeps recommending M6, and esp over tightening recommendation to 15N.m⌠At least the Gong has lots of support mast to fuselage
Tensile strength of Grade 2 Titanium screws 50,000 psi. Most common type available.
Tensile strength of high strength 316 stainless screws 110,000 psi or 70,000 psi for regular. Most common types.
Many users misunderstand the reasons to use titanium and jump to the conclusion that more expensive is better.
Titanium was introduced to foiling by Armstrong. It created a me-too movement that never should have happened.
Stainless is twice the strength and better in all aluminum applications.
Titaniumâs only purpose is to avoid carbon fiber from attacking stainless steel in salt water. Titanium and carbon fiber play better together in salt water. But, you donât need titanium at all with carbon fiber, provided the customer doesnât get his panties in a bunch over slightly brown color stains on stainless screws from carbon touching it in salt water. In many cases the slightly brown stains come from customers cross contamination of using tools that are not also stainless steel.
I replaced the standard screws with the titanium ones (also M6x32 from the F-One shop) after the middle one cracked during a start (loud bang, stopped pumping and swam back to dock).
Yes my weight and 1900 is probably too much (apparently lol).
Any hints what i should aim for now? JAM 1400? Different manufacturer? Axis, Gong, Sabfoil?
Real bummer the 1900 sits at the bottom of the lake now, i liked the performance.
If you havenât already and seeing as it seems the screws you used were pretty new and from an F-One dealer you should definitely get in contact with them regarding warranty/compensation. Or even contact F-One directly if no dice with your shop.
Iâve heard of others cases of planes getting lost at the bottom and F-One making the situation right by replacing the lost gear, hope it works out for you !
Agree on the misconception around titanium-strength to weight is much higher but the extra mass is of no importance in this setting. Also it is more brittle and should only be tightened with a torque wrench. I was almost killed by failing titanium on a two bolt bicycle stem that suddenly failed at speed and i went head first to ground. Only use stainless in critical spots since.,
speaking from experience - Iâve lost two foil setups over the years. One washed up on shore at the beach, the other is still at the bottom of a lagoon despite repeated snorkeling attempts to find it.
The Takuma setup had M6 bolts and Iâm almost positive they had come slightly loose. When one or more of the fasteners get loose, the loads get really high. If you ever feel any extra wobble in the setup you have to quit right away and go in to tighten things up, donât wait.
I wonât buy another setup based on M6 anymore. M8 stainless all the way for me
If running one of these m6 setups you MUST be testing the setup for movement every session. Grab the connection area with one hand and flex on the wingtip HARD. If thereâs movement youâll feel it. Movement means those fasteners are bending and work hardening and going to fail.
i was testing for wobble before every start (foil in water and shaking it). sometimes i noticed wobble coming from the mast to top plate or mast to foot every 2nd or 3rd session and fixed it. never had foil to mast foot being shaky with the titanium bolts (standard bolts came loose sometimes tho)
so yea im going to look for an M8 setup for a high AR foil and probably only riding it on 60cm to reduce any flex
edit
im reviewing the old standard screws right now. apart from the broken one, another one is severely deformed:
see picture
I much prefer a system that doesnât use screws as a structural component. The strength should be designed in, with screws only serving one purpose. Not to let it fall apart. This is the concept followed by Code, Lift, Axis, etc. Code being my personal favorite. The newest design of the three, and the most robust engineering.
Grade 2 titanium should never be used on any part of your foil. Itâs very weak. If itâs grade 5, it is quite a bit stronger than stainless steel (any common grade you will likely run across) but when it fails, it will probably fail with absolutely no warning with a snap. If it doesnât say âgrade 5â or â6Al-4Vâ itâs probably grade 2.
Iâd like to add one recommendation to thisâŚif the screws were tight and now theyâre not (and you didnât touch anything), itâs entirely possible that the screw has stretched like in the posted pic below. At that point, the strength is completely compromised. Attempting to retighten and go again is a bad idea.
You can even feel stretch with a new good condition standard stainless steel screw. If you carefully tighten one, you can feel thereâs a point where it starts to stretch if you know what to look/feel for. If you have a good titanium screw or a high strength stainless screw (very uncommon and hard to findâŚlook for something with â-80â somewhere in the description), when you tighten it down, the feel is very different. Itâs like it tightens down then suddenly gets much tighter and will make you feel like you should stop. Kind of like hitting a wall. This is because the yield strength is higher and itâs not stretching. I also notice this with M8 screws into aluminum vs M8 screws into aluminum with a helicoil. In this case, I believe itâs the bare aluminum thatâs stretching rather than the screw.
Yea in an application like this I would consider the screws to be one time use. Tighten them to spec once and if it ever has a wobble in the future or you ever disassemble it for any reason you replace the fasteners.
Definitely.
Everytime I see a mast carbon cracking, bolts snapping, inserts tearing, itâs AFS or Fone.
Even with light riders and small wings.
These connections systems arenât designed to last.
Code is my daily driver.
But Axis has the best connection system.
Having a metal fuselage that expends when inserting the carbon mast in it makes the connection ultra tight.
With Code, the carbon wears out and the connection is less tight.
Sure recsating with a thin layer of epoxy isnât a big deal.
Even the Axis footing eventually wears out and needs either some sort of shimming or repotting.
Things are ultratight initially then less and less over time. Thatâs the way of things with tapered fittingâŚ
For sure M8 stainless should be the norm, whatever the connection.
I must say GoFoil overall assembly is absolutely bombproof in that regard, even if itâs a pain in the ass for travelling, itâs pretty much unbeatable for reliability.
It funny you mention GoFoil, back when I started GoFoil was pretty much all there was for larger foils, and they assembled with only 2 screws, had a âmonoblocâ front wing/fus and monobloc rear tail, so many features we think of as new and modern in the latest foils . . .
I donât know how often you take the foil apart but you can wrap electric tape around the fuse and the mast foot, both trailing and leading edge. In case in breaks, the tape might hold on to the foil. Or a fishing line around mast then to the fuse. fishing line quick clip, should allow quick disassemble. It shouldnât cause too much drag.
when i heard a sudden snap and instantly hit the water with board. Didnt do anything crazy, just going straight.
